AM-FM extraction based on logarithmic differential decomposition
Nobutaka Ono, Mototsugu Abe, Shigeru Ando · 1999
The most important features of quasi-harmonic signals such as speech or musical sounds are the instantaneously varying amplitude (AM) and pitch (FM) of the harmonics. However, when we want to recognise them after subband decomposition like a human cochlea, the problem is that AM-FM components of the original harmonics are disturbed both by the filtering and the interference between harmonics. In this paper, we propose a method of logarithmic differential decomposition (LDD) and a new AM-FM extraction algorithm based of it. It extracts separately the conventional AM-FM which are common to all the harmonics and the interferometric AM-FM which are synchronous with pitch, hence can be an efficient clue to determine the fundamental. We investigate the role of those features by experiments for speech.